if (IS_NOCMTIME(inode)) return;- if (IS_RDONLY(inode))+ /*+ * Ideally, we want to guarantee that 'f_vfsmnt'+ * is non-NULL here. But, NFS exports need to+ * be fixed up before we can do that. So, check+ * it for now. - Dave Hansen+ */+ if (file->f_vfsmnt)+ err = mnt_want_write(file->f_vfsmnt);+ if (err) return;